The study employs two bacterial differentiating systems: sporulation in Bacillus species and encystment in Azotobacter vinelandii. Bacitracin production in B. licheniformis begins at the onset of sporulation. We propose that this antibiotic functions early in the process. We have isolated a triple mutant unable to synthesize ornithine, a constituent of bacitracin, and can thus test the hypothesis that this peptide antibiotic in free or combined form plays a distinct physiological role in the cell. We will continue our study of the control of turnover of proteins during the sporulation of B. licheniformis. The enzyme arginase will be pulse labelled with radioactive amino acids and then monitored by enzymatic assay and immunoprecipitation to determine whether its increase is actually the summation of synthesis and turnover. The pathway of synthesis of 5-alkyl-1-,3-resorcinols will be studied by C13 and O18 labelling of substrate with product identification by mass spectrometry. The effect of various small molecules on nitrogenase will be examined with a view to determining the nature of the NH3 sensing mechanism of the Azotobacter cells and how control is exerted at the level of the enzyme and phe nif gene.